Contemporary hard disk drives include a head stack assembly pivoting through an actuator pivot to position one or more read-write heads, embedded in sliders, each over a disk surface. The data stored on the disk surface is typically arranged in concentric tracks. To access the data of a track, a servo controller first positions the read-write head by electrically stimulating the voice coil motor, which couples through the voice coil and an actuator arm to move a head gimbal assembly in lateral positioning the slider close to the track. Once the read-write head is close to the track, the servo controller typically enters an operational mode known as track following. It is during track following mode that the read-write head is used to access the data stored of the track. Micro-actuators provide a second actuation stage for lateral positioning the read-write head during track following mode. They often use an electrostatic effect and/or a piezoelectric effect to rapidly make fine position changes. They have doubled the bandwidth of servo controllers and are believed essential for high capacity hard disk drives from hereon. Recently, vertical micro-actuators have begun to be used to create what is sometimes referred to as flying height on demand.
What is perpetually needed are mechanisms and methods supporting increased reliability in accessing the tracks on the rotating disk surface of a hard disk drive. Toward that end, it has been understood for some time that the ambient air temperature affects the operations of a hard disk drive. To the inventors' knowledge, no one has previously recognized the significance of humidity on these operations. This invention begins by recognizing a problem where no one previously knew one existed, and then solving that problem.